1. Field of the Invention
This invention relates generally to cables, and more particularly to improved cables used to interconnect computer systems to external peripheral devices.
2. Description of the Related Art
Personal computers provide today's users with the power to communicate with other networked users, share information and access data from peripheral devices. As is well known, personal computers are capable of being connected to a variety of peripheral devices, such as, fixed and removable storage drives, scanners, compact discs, etc. To achieve high performance data transfer interfaces between the host computer system and a given peripheral device, computer users typically use hardware that can take advantage of the small computer system interface (SCSI) protocol. Typically, a computer is provided with SCSI capabilities via SCSI controller cards that connect to the host computer or via a SCSI chip that is integrated as part of the computer's motherboard. Once a computer is provided with SCSI capabilities, the user is able to connect either internal or external SCSI peripheral devices to the computer. Internally, SCSI ribbon cables are used to interconnect the peripheral devices to the computers controller card or a motherboard's connector. Externally, SCSI peripheral devices can be coupled to the computer's connector receptacle via an external SCSI cable.
FIG. 1A illustrates a computer system 10 having a SCSI peripheral device (PD) 12 connected thereto. Generally, a SCSI cable 14 is connected to a SCSI controller connector located on the backside of the computer system's housing. The other end of the SCSI cable 14 has a connector 16 that couples to the SCSI peripheral device 12. Unfortunately, SCSI cables 14 which comport to the rigorous SCSI electrical specification requirements are designed having thick and rigid physical characteristics. For instance, SCSI cable 14 typically has an outer diameter of about 1/2 inch. Although the SCSI protocol has evolved through several generations to provide enhanced throughput capabilities, the physical makeup of the cabling has remained substantially the same. As a result, the SCSI protocol itself is sometimes viewed by consumers as behind the times, simply because the cabling appears thick, bulky, and is extremely rigid.
FIG. 1B shows a magnified view of the SCSI cable 14 and its internal contents. As shown, the SCSI cable typically has an outer jacket that covers a braided conductive shield 18. The braided conductive shield 18 covers several layers of tightly wrapped plastic and an insulative cover 20. The tightly wrapped plastic and insulative cover 20 is configured to enclose the plurality of wires 22, which lead to the connector 16, which may be a 50 pin or 68 pin connector. Although there has been a desire to reduce the physical size of the SCSI cable 14, cable designers were largely prevented from completing this task because the SCSI ANSI X3.131 standard for SCSI-1, SCSI-2, and SCSI-3, imposes strict electrical characteristic requirements. In addition, present manufacturing techniques and tooling for conventional SCSI cables are not capable of producing cables with thinner dimensions.
Beyond the fact that conventional SCSI cables 14 place an improper stigma on the SCSI protocol as a whole as being outdated, users of today's computer systems also demand that external cabling be more flexible and capable of spanning longer distances. For instance, users sometimes like to place the housing of the computer system under a desk or at a location that is spaced apart from the computer monitor. At the same time, the user may want to place external peripheral devices, such as, second hard drives, removable drives, scanners, CD ROMs, CD-Rs, CD-RWs, on the desk top near the monitor so as to provide easy access during a working session. Conventional SCSI cables that meet the full SCSI electrical specification are quite short, spanning distances of approximately 2 to 3 feet. The length limitation, coupled with the thick and bulky nature of the SCSI cable, thus reinforces the improper image of SCSI being old and outdated.
Furthermore, because conventional SCSI cables are not very flexible, when a connection is made to the computer housing, the computer housing is sometimes required to be arranged in an awkward way, so as to avoid accidental unplugging. That is, because the conventional SCSI cable resists bending, movement of the computer housing can in some cases cause the connector to be partially unplugged. Consequently, the physical nature of the SCSI cable can introduce a level of unreliability, which can hamper a computer user's image of SCSI and the user's desire to use SCSI for interconnecting to and from external peripheral devices.
In view of the foregoing, there is a need for SCSI cables that have smaller diameters, have improved flexibility, and have the ability of spanning longer distances, while continuing to meet the cabling electrical characteristics set forth in the SCSI standard.